SULFUR HEXAFLUORIDE by portable GC
SF6
MW: 146.06
METHOD: 6602
CAS: 2551-62-4
RTECS: WS4900000
EVALUATION: FULL
OSHA : 1000 ppm NIOSH: 1000 ppm ACGIH: 1000 ppm (1 ppm = 5.97 mg/m 3 @ NTP)
PROPERTIES:
6602
Issue 1: 15 August 1994
colorless, odorless gas; MP -50.8 °C; sublimes -63.8 °C; d = 5.0 (air = 1)
SYNONYMS: (none)
SAMPLING
MEASUREMENT
SAMPLER:
GAS SAMPLING BAG
TECHNIQUE:
GAS CHROMATOGRAPHY (PORTABLE)
FLOW RATE:
0.02 to 0.1 L/min; fill bag ≤ 80% of capacity; spot samples (step 2.a.) or TWA samples (step 2.b.)
ANALYTE:
sulfur hexafluoride
COLUMN:
38 cm x 6-mm OD stainless steel, packed with 100-120 mesh activated alumina
stable 28 h in 5-layers bags; 8 h in Tedlar bags
DETECTOR:
electron capture
CALIBRATION:
bag standards or calibrated gas mixtures
RANGE:
0.1 to > 10,000 ppb
SAMPLE STABILITY:
FIELD BLANKS:
in bag from a non-work area
ESTIMATED LOD: 0.05 ppb PRECISION (Sr):
0.022
ACCURACY RANGE STUDIED:
0.1 to 200 ppb
BIAS:
- 0.4%
ˆ ): 0.022 OVERALL PRECISION (S rT ACCURACY:
± 4.8%
APPLICABILITY: The working range of this method is 0.1 to 10,000 ppb in relatively non-complex atmospheres where sulfur hexafluoride is known to be present, such as indoor environments where ventilation testing is being conducted by the rel ease of SF6.
INTERFERENCES: Any compound having the same or nearly the same retention time as sulfur hexafluoride on the column may cause a positive interference. Carbon dioxide, another common substance monitored to evaluate ventilation systems in ind oor air quality studies, will not interfere.
OTHER METHODS: Method S244 [1] describes the determination of SF 6 by thermal conductivity detection after collection in bags, with a lower limit of 500 ppm, i.e., not sensitive enough for ventilation studies.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94
